Steam turbine plant

ABSTRACT

The object of the present invention is to carry out a highly efficient power generation or to efficiently use an exhaust heat of a low temperature. A steam turbine plant includes a steam turbine  1  and a heating unit configured to heat a working fluid to be supplied to the steam turbine  1 . The heating unit includes a first heat source  14  using a fossil fuel or a second heat source  8  using an extracted steam from the steam turbine  1 , and a third heat source  44  not using a fossil fuel but using a waste exhaust combustion gas.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2013-185682 filed on Sep. 6,2013, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

An embodiment of the present invention relates to a steam turbine plant.

BACKGROUND ART

A steam turbine plant using a coal fired boiler 7 is described withreference to FIG. 13. A feed water 42 is transported to the coal firedboiler 7 by a feed pump 6, and is heated therein to change to a steam 2.Since the coal fired boiler 7 heats the feed water 42 by an exhaustcombustion gas 13 that is generated by burning a coal 43, the coal firedboiler 7 is a heat source derived from a fossil fuel. FIG. 13 simplyillustrates the exhaust combustion gas 13, the coal 43 flowing into thecoal fired boiler 7 and a combustion air 12.

The steam 2 flows into a steam turbine 1 and expands inside the steamturbine 1, so that a pressure and a temperature thereof lower. A turbineexhaust gas 3 flows into a condenser 4. The turbine exhaust gas 3 iscooled by a cooling water in the condenser 4 to become a condensation 5.The condensation 5 merges with a drainage water 10 described below tobecome a feed water 42 so as to be circulated. Although not shown, thecooling water is drawn up by a not-shown cooling water pump from sea,and is then transported to the condenser 4. After heated in thecondenser 4, the cooling water is returned to the sea.

A rotating shaft of the steam turbine 1, which is rotated by theexpanding steam 2, is connected to a not-shown generator. Power isgenerated in the generator by using a generated shaft power. Anextraction steam 8 extracted from a middle location of the steam turbine1 flows into a feed water heater 9 so as to heat the feed water 42transported by the feed pump 6. At this time, the extraction steam 8condenses to become the drainage water 10, and finally merges with thecondensation 5. When no steam is extracted from the steam turbine 1, thecondensation 5 becomes the feed water 42 as it is.

A steam turbine plant constituting a part of a combined cycle isdescribed with reference to FIG. 14. The same part as the techniqueshown in FIG. 13 is shown by the same reference number and detaileddescription thereof is omitted. Only a part different from the techniqueshown in FIG. 13 is described. A gas turbine exhaust gas 14 from anot-shown gas turbine, which has a sufficiently high temperature, iscaused to flow into an exhaust gas boiler 15. A feed water 42 istransported to the exhaust gas boiler 15 by a feed pump 6, and is heatedtherein by the gas turbine exhaust gas 14 to change to a steam 2. Sincea gas turbine generates an exhaust combustion gas by burning a naturalgas or a town gas so as to be driven by the gas turbine exhaust gas 14,the exhaust gas boiler 15 is a kind of a heat source derived from afossil fuel. After a temperature of the gas turbine exhaust gas 14lowers, the gas turbine exhaust gas 14 flows out from the exhaust gasboiler 15. An extraction steam 8 is not extracted from a middle locationof the steam turbine 1 in FIG. 14. However, similarly to FIG. 13, theextraction steam 8 may be extracted from a middle location of the steamturbine 1 and may be caused to flow into a feed water heater 9 so as toheat a feed water 42.

In a Rankine cycle, the higher the temperature and the pressure of asteam turbine inlet steam are, the higher the efficiency, i.e., thevalue of a steam turbine output with respect to a heat quantity receivedfrom a heating source is. A value obtained by multiplying a generatorefficiency by the output is a power generation quantity. FIG. 18 shows aTS line diagram in which an axis of ordinate shows a temperature of aworking fluid and an axis of abscissa shows an entropy. Curves 32 and 33are a saturated liquid line and a saturated steam line. A steam turbineinlet, a steam turbine outlet (condenser inlet), a condenser outlet(feed pump inlet), and a feed pump outlet are shown by the referencecharacters e, f, a and b in FIG. 18. An area A is an area that issurrounded by “a, b, c, d, e and f”, and an area B is an area that issurrounded by “f, j, k and a”. A received heat quantity, a heat quantityto be released to a cooling water and a steam turbine output correspondto superficial dimensions of the areas A+B, the area B and the area A,respectively. The efficiency corresponds to an area ratio A/(A+B).

When a steam turbine inlet has a higher temperature and a higherpressure, a steam turbine inlet is “i” in FIG. 18, and the area A is anarea A′ that is surrounded by “a, b, c, g, h, i and f”. The area Bcorresponding to a heat quantity to be released to a cooling water isunchanged. The areas A+B and the area A corresponding to a received heatquantity and a steam turbine output are changed to areas A′+B and anarea A′, respectively. Thus, the area ratio A′/(A′+B) is larger thanA/(A+B). For this reason, an efficiency improves.

A general waste power generation is described with reference to FIG. 15.The same part as the technique shown in FIG. 13 is shown by the samereference number and detailed description thereof is omitted. Only apart different from the technique shown in FIG. 13 is described. A wasteboiler 18 burns a waste, so as to heat water by a waste exhaustcombustion gas 44. The waste exhaust combustion gas 44, a waste 11flowing into the waste boiler 18 and a combustion air 12 are brieflyillustrated. A feed water 42 is transported to the waste boiler 18 by afeed pump 6, and is heated therein to change to a steam 2. Since thewaste exhaust combustion gas 44 contains a corrosive gas such ashydrogen chloride, a heat cannot be recovered only at a temperature thatdoes not cause a high temperature corrosion in a boiler heat exchangertube. In many cases, when a tube wall temperature of a boiler heatexchanger tube exceeds about 320° C., a high temperature corrosion ismore likely to occur therein. Thus, a steam temperature is generally300° C. or less, for example. For this reason, a steam turbine inlettemperature cannot be raised only up to 300° C., for example. Althoughthere is a case in which a steam turbine inlet temperature can be raisedmore, a steam turbine inlet temperature can be raised only up to 400° C.or less at most. In the Rankine cycle, when the temperature and thepressure of the steam turbine inlet are higher, an efficiency can beraised. That is to say, a power generation efficiency cannot be raised.The waste power generation produces electricity after a waste has beenappropriately treated. In order to make good use of an exhaust gasgenerated by the waste treatment, power generation is carried outalthough the efficiency is low.

A general geothermal power generation is described with reference toFIG. 16. The same part as the technique shown in FIG. 13 is shown by thesame reference number and detailed description thereof is omitted. Onlya part different from the technique shown in FIG. 13 is described. Ageothermal steam 19 taken out from a ground 21 is caused to flow into asteam separator 45, so that the geothermal steam 19 is separated into asteam 2 and a hot water 20. The steam 2 flows into a steam turbine 1.The steam 2 expands inside the steam turbine 1, so that a pressure and atemperature thereof lower. A turbine exhaust gas 3 is released outside.Since a steam temperature is not more than 350° C. in most cases, asteam turbine inlet temperature cannot be raised so that a powergeneration efficiency cannot be raised. In addition, a heat held by thehot water 20 is not efficiently used.

A general solar heat power generation is described in described withreference to FIG. 17. The same part as the technique shown in FIG. 13 isshown by the same reference number and detailed description thereof isomitted. Only a part different from the technique shown in FIG. 13 isdescribed. A heating medium 24 receives a radiant heat of solar light soas to be heated in a solar heat collector 23. The heated heating medium24 is diverged into two. One heating medium flows into a solar heatheater 22, and the other heating medium flows into a heat storage tank25. A heating medium pump 27 is adjusted such that the heating mediumflows in a direction drawn by a solid line on the left side of the heatstorage tank 25. A part of the heating medium 24 flows into the solarheat heater to heat a feed water 42 to lose its temperature, and flowsout therefrom. When a remaining part of the heating medium 24, which hasheated the feed water 42, flows into the heat storage tank 25, theheating medium, which has been already therein and has a lowertemperature, flows out from the heat storage tank 25, so that theheating medium 24 of a higher temperature is stored in the heat storagetank 25 in the end. After the heating medium 24 has been stored, valves30 and 31 are totally closed. The heating medium 24 is transported byheating medium pumps 26 and 27. The feed water 42 is transported to thesolar heat heater by a feed pump 6, and is heated therein to change to asteam 2. During a nighttime when no solar light exists or a time zonewhen only weak solar light exists, valves 28 and 29 are closed and theheating medium pump 26 is stopped, while the valves 30 and 31 are openedand the heating medium pump 27 is operated, so that the heating mediumflows in a direction drawn by dotted lines on the right side of the heatstorage tank 25. The feed water 42 is heated by circulating the heatingmedium 24 between the heat storage tank 25 and the solar heat heater 22,without circulating the heating medium 24 through the solar heatcollector 23.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: JP2008-39367A

Patent Document 2: JP2008-121483A

SUMMARY OF THE INVENTION

In the techniques shown in FIGS. 15 and 16, since a steam turbine inlettemperature cannot be raised, a power generation efficiency cannot beraised like the techniques shown in FIGS. 13 and 14. Thus, improvementin power generation efficiency is desired. In addition, in the techniqueshown in FIG. 16, a heat held by the hot water 20 is desired to beefficiently used for power generation.

A fuel battery is a power generation method that is different from aturbine. The fuel battery releases a large amount of exhaust heat.However, an exhaust heat temperature is considerably lower than atemperature suited for a working fluid of a steam turbine. In addition,an industrial exhaust heat from factories and offices is dischargedwithout being efficiently used. In most cases, a temperature of theexhaust heat is considerably lower than a temperature suited for aworking fluid of the steam turbine 1. It is desired that these exhaustheats are efficiently used to generate power.

The object of the present invention is to carry out a highly efficientpower generation by using a heat source whose steam turbine inlettemperature cannot be raised, and to generate power by efficiently usingan exhaust heat having a considerably low temperature.

A steam turbine plant according to one embodiment is a steam turbineplant including: a steam turbine; and a heating unit configured to heata working fluid to be supplied to the steam turbine; wherein: theheating unit is configured to heat the working fluid by a first heatsource using a fossil fuel or a second heat source using an extractedsteam from the steam turbine; and the heating unit is configured tofurther heat the working fluid in a low temperature zone by a third heatsource other than a solar heat, the third heat source not using a fossilfuel.

A steam turbine plant according to another embodiment is a steam turbineplant including: a steam turbine; and a heating unit configured to heata working fluid to be supplied to the steam turbine; wherein: theheating unit is configured to heat the working fluid by a fourth heatsource using a solar heat or a second heat source using an extractedsteam from the steam turbine; the heating unit is configured to furtherheat the working fluid in a low temperature zone by a fifth heat sourceother than a solar heat; and the fifth heat source includes anindustrial exhaust heat.

A steam turbine plant according to yet another embodiment is a steamturbine plant including: a steam turbine; and a heating unit configuredto heat a working fluid to be supplied to the steam turbine; wherein:the heating unit is configured to heat the working fluid by a fourthheat source using a solar heat or a second heat source using anextracted steam from the steam turbine; the heating unit is configuredto further heat the working fluid in a low temperature zone by a fifthheat source other than a solar heat; and the fifth heat source includesan exhaust heat of a fuel battery or an internal combustion engine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual view showing a steam turbine plant according to afirst embodiment.

FIG. 2 is a conceptual view showing a steam turbine plant according to asecond embodiment.

FIG. 3 is a conceptual view showing a steam turbine plant according to athird embodiment and a fourth embodiment.

FIG. 4 is a conceptual view showing a steam turbine plant according to afifth embodiment.

FIG. 5 is a conceptual view showing a steam turbine plant according to asixth embodiment.

FIG. 6 is a conceptual view showing a steam turbine plant according to aseventh embodiment.

FIG. 7 is a conceptual view showing a steam turbine plant according toan eighth embodiment and a ninth embodiment.

FIG. 8 is a conceptual view showing a steam turbine plant according to atenth embodiment.

FIG. 9 is a conceptual view showing a steam turbine plant according toan eleventh embodiment.

FIG. 10 is a conceptual view showing a steam turbine plant according toa twelfth embodiment and a thirteenth embodiment.

FIG. 11 is a conceptual view showing a steam turbine plant according toa fourteenth embodiment.

FIG. 12 is a conceptual view showing a steam turbine plant according toa fifteenth embodiment.

FIG. 13 is a conceptual view showing a steam turbine using a coal firedboiler.

FIG. 14 is a conceptual view showing a steam turbine of a combinedcycle.

FIG. 15 is a conceptual view showing a technique of waste powergeneration.

FIG. 16 is a conceptual view showing a technique of geothermal powergeneration.

FIG. 17 is a conceptual view showing a technique of solar powergeneration.

FIG. 18 is a TS line diagram of a Rankine cycle.

FIGS. 19( a) and (b) are conceptual views showing an effect of theembodiments.

EMBODIMENTS FOR CARRYING OUT THE INVENTION First Embodiment

A steam turbine according to a first embodiment is described withreference to FIG. 1.

As shown in FIG. 1, a gas turbine exhaust gas 14 from a not-shown gasturbine, which has a sufficiently high temperature, is caused to flowinto an exhaust gas boiler 15. A feed water 42 is transported to theexhaust gas boiler 15 by a feed pump 6, and is heated therein by a gasturbine exhaust gas 14 to change to a steam 2. Since the gas turbinegenerates an exhaust combustion gas by burning a natural gas or a towngas so as to be driven by the gas turbine exhaust gas 14, the exhaustgas boiler 15 is a heat source derived from a fossil fuel (first heatsource).

After a temperature of the gas turbine exhaust gas 14 lowers, the gasturbine exhaust gas 14 flows out from the exhaust gas boiler 15. Thesteam 2 flows into the steam turbine 1, and expands inside the steamturbine 1, so that a pressure and a temperature thereof lower. A turbineexhaust gas 3 from the steam turbine 1 flows into a condenser 4. Theturbine exhaust gas 3 is cooled by a cooling water in the condenser 4 tobecome a condensation 5. Although not shown, the cooling water is drawnup by a not-shown cooling water pump from sea, and is then transportedto the condenser 4. After heated in the condenser 4, the cooling wateris returned to the sea. A rotating shaft of the steam turbine 1, whichis rotated by the expanding steam 2, is connected to a not-showngenerator. Power is generated in the generator by using a generatedshaft power.

As shown in FIG. 1, a waste boiler 18 is installed as a heater. To bespecific, the feed water 42 is diverged into a second feed water 35 anda third feed water 36. The second feed water 35 is transported to theexhaust heat boiler 15, and is heated therein by the gas turbine exhaustgas 14 so as to have a higher temperature. The third feed water 36 flowsinto the waste boiler 18 as a heater, and is heated by a waste exhaustcombustion gas (third heat source) 44, which is generated by burning awaste 11 and a combustion air 12, so as to have a higher temperature.Since a pressure of the third feed water 36, which is equal to apressure of the second feed water 35 for a high-temperaturehigh-pressure turbine, is higher than a pressure for a waste, powergeneration, the third feed water 36 does not basically boil. Thus, thewaste boiler 18 functions only as a hot water boiler. After that, thethird feed water 36 flows into a middle location of the exhaust heatboiler 15, and merges with the second feed water 35, which has beenheated by the exhaust heat boiler 15, at a merging point 34. Atemperature of the third feed water 36 is restricted in terms of hightemperature corrosion. It is preferable that the merging point 34 islocated such that the temperature of the second feed water 35 and thetemperature of the third feed water 36 are substantially equal to eachother, but it is not a must.

In the waste boiler 18, a composition of the waste 11 and an amount ofthe waste 11 to be treated may considerably vary, but a property of thesteam 2 flowing into the steam turbine 1 should not considerably vary.In a general steam turbine plant, a temperature and a pressure of thesteam 2 are measured, and the temperature and the pressure should notconsiderably vary. In addition, in a general steam turbine plant, a flowrate of the steam 2 is obtained by measuring a flow rate of the feedwater 42, for example, and the flow rate of the steam 2 should notconsiderably vary.

For this reason, it is preferable that an output of the feed pump 6 isadjusted so as to adjust a flow rate and a pressure of the feed water42, that a flow rate ratio between the second feed water 35 and thethird feed water 36 is adjusted by adjusting opening degrees of thevalves 37 and 38, and that, depending on cases, an amount of the waste11 to be treated is increased or decreased, in order that thetemperature, the pressure and the flow rate of the steam 2 do notconsiderably vary. At this time, although not shown, a flow-rateadjusting valve may be installed on a downstream of the feed pump 6, soas to adjust the flow rate and the pressure of the feed water 42 byadjusting an opening degree of the flow-rate adjusting valve. A pressureof the third feed water 36, which is a working fluid of the waste boiler18, is adjusted by the feed pump 6. The pressure of the third feed water36 is a pressure for a high-temperature high-pressure turbine, similarlyto the technique shown in FIG. 14. Thus, the pressure of the third feedwater 36 is higher than that in the technique shown in FIG. 15. In FIG.18, the merging point 34 is shown by 1. If the pressure of the thirdfeed water 36 at the merging point 34 is higher and the third feed water36 is changed to a saturated steam, it is preferable that a wetness ofthe second feed water 35 and a wetness the third feed water 36 aresubstantially equal to each other, but it is not a must. The mergedwater is further heated by the exhaust heat boiler 15 so as to change tothe steam 2. Then, the steam 2 flows into the steam turbine 1. In FIG.18, the water is heated in parallel by two kinds of heat sources from bto l, and is heated by one kind of heat source from l to i. When thethird feed water 36 is not circulated because the waste boiler 18 isstopped and the like, the valves 37 and 38 are totally closed. Ingeneral, since a steam flow rate in the waste power generation issufficiently smaller than a steam flow rate in the combined cycle, evenif the flow rate of the steam 2 somewhat lowers, the steam turbine 1 canbe operated.

Suppose that the exhaust heat boiler 15 and the waste boiler 18 areconnected in series with respect to the water. In this case, since atemperature of the gas turbine exhaust gas 14 does not lower down to awater temperature at an outlet of the waste boiler 18, a heat of the gasturbine exhaust gas 14 cannot be recovered at a temperature lower thanthat. On the other hand, according to this embodiment, since an upstreamside of the exhaust heat boiler 15 and the waste boiler 18 are inparallel with respect to the feed water, a heat recovery from the gasturbine exhaust gas 14 will not be restricted for its existence. Inaddition, an outlet temperature of the exhaust gas of the exhaust heatboiler 15 is equal to the technique shown in FIG. 14, a received heatquantity from the exhaust heat boiler 15 is equal to the technique shownin FIG. 14. Thus, as the Rankine cycle, a received heat quantity isincreased by a heat received from the waste boiler 18, so that a flowrate of the steam 2 is increased to increase an output, while a steamturbine inlet temperature is unchanged. An efficiency of the Rankinecycle is determined only by the area ratio in the TS line diagram,regardless of a flow rate. Since all the steam constitutes the Rankinecycle of a high temperature and a high pressure, an efficiency accordingto this embodiment is equal to the technique shown in FIG. 14. Inaddition, as compared with a case in which the technique shown in FIG.14 and the technique shown in FIG. 15 separately exist, an output ofthis embodiment is large and an efficiency is high even if the samereceived heat quantity is generated. Thus, a highly efficient powergeneration can be carried out by using the heat from the waste boiler 18from which a highly efficient power generation was impossible. Since theoperation of the gas turbine is not influenced, there is no possibilitythat a power generation output and an efficiency of the gas turbine aredegraded.

The structure shown in FIG. 1 is nothing more than an example, and themerging point at which the second feed water 35 and the third feed water36 merge with each other may not the middle location of the exhaust heatboiler 15, but may be a location that is downstream of the outletthereof. In addition, similarly to FIG. 13, an extraction steam 8extracted from a middle location of the steam turbine 1 may be caused toflow into a feed water heater 9 so as to heat the feed water 42.

An effect of this embodiment is described with reference to FIG. 19. Asshown in FIG. 19( a), a feed water is heated from a condensationtemperature to a steam turbine inlet temperature in the followingmanner. The feed water of a lower temperature zone of a lowertemperature is heated by the exhaust heat boiler 15 using the heatsource derived from a fossil fuel (first heat source) and the wasteexhaust combustion gas which is the heat source other than a fossil fuel(third heat source). The feed water of a higher temperature zone of ahigher temperature is heated by the exhaust heat boiler 15 using theheat source derived from a fossil fuel (first heat source).

In this manner, since the feed water of the lower temperature zone isheated also by the waste exhaust combustion gas, and a high temperaturesteam flowing into the the steam turbine 1 is reliably generated by thethe exhaust heat boiler 15 derived from a fossil fuel, the waste exhaustcombustion gas of a lower temperature, which has not been usedheretofore in the steam turbine 1, can be efficiently used to improve apower generation efficiency.

Second Embodiment

Next, the steam turbine plant according to a second embodiment isdescribed with reference to FIG. 2.

In the steam turbine plant shown in FIG. 2, the same part as that of thesteam turbine plant shown in FIG. 1 is shown by the same referencenumber and detailed description thereof is omitted.

As shown in FIG. 2, there is installed a heater 47 for heating a steam 2by a geothermal steam 19. Differently from the technique shown in FIG.16, in FIG. 2, the geothermal steam 19 (third heat source) taken outfrom a ground 21 is caused to flow directly into a heater 47. A thirdfeed water 36 flows into the heater 47 and is heated by the geothermalsteam 19 so as to have a higher temperature. Since a pressure of the thethird feed water 36 is equal to a pressure of the second feed water 35for a high-temperature high-pressure turbine, the third feed water 36does not basically boil. After that, the third feed water 36 flows intoa middle location of an exhaust heat boiler 15, and merges with thesecond feed water 35, which has been heated by the exhaust heat boiler15. A temperature of the third feed water 36 is not raised to atemperature of the geothermal steam 19. It is preferable that themerging point 34 is located such that the temperature of the second feedwater 35 and the temperature of the third feed water 36 aresubstantially equal to each other, but it is not a must.

A flow rate and a temperature of the geothermal steam 19 mayconsiderably vary, but a property of the steam 2 flowing into the steamturbine 1 should not considerably vary. In a general steam turbineplant, a temperature and a pressure of the steam 2 are measured, and thetemperature and the pressure should not considerably vary. In a generalsteam turbine plant, a flow rate of the steam 2 is obtained by measuringa flow rate of the water 42, for example, and the flow rate of the steam2 should not considerably vary.

For this reason, it is preferable that an output of the feed pump 6 isadjusted so as to adjust a flow rate and a pressure of the feed water42, that a flow rate ratio between the second feed water 35 and thethird feed water 36 is adjusted by adjusting opening degrees of valves37 and 38, and that, depending on cases, a flow rate of the geothermalsteam 19 is increased or decreased by a not-shown flow-rate adjustingvalve, in order that the temperature, the pressure and the flow rate ofthe steam 2 do not considerably vary. At this time, although not shown,a flow-rate adjusting valve may be installed on a downstream of the feedpump 6, so as to adjust the flow rate and the pressure of the feed water42 by adjusting an opening degree of the flow-rate adjusting valve.Since a pressure of the third feed water 36, which is adjusted by thefeed pump 6, is a pressure for a high-temperature high-pressure turbinesimilarly to the technique shown in FIG. 14, the pressure of the thirdfeed water 36 is higher than a pressure of the geothermal steam 19 inthe technique shown in FIG. 16. Thus, the third feed water 36 does notboil even partially. A merging point 34 is shown by m in FIG. 18. Themerged water is heated by the exhaust heat boiler 15 so as to change toa steam 2. Then, the steam 2 flows into the steam turbine 1. In FIG. 18,when the merging point 34 is shown by m, the water is heated in parallelby two kinds of heat sources from b to m, and is heated by one kind ofheat source from m to i. When the third feed water 36 is not circulatedthrough a heater 47 for some reason or other, the valves 37 and 38 aretotally closed. Since a flow rate of the third feed water 36 issufficiently smaller than a flow rate of the second feed water 35, evenif the flow rate of the steam 2 somewhat lowers, the steam turbine 1 canbe operated.

In the technique shown in FIG. 16, a temperature of the steam 2separated by a steam separator 45 is the same as a temperature of thegeothermal steam 19. On the other hand, according to this embodiment,since the third feed water 36 is heated by the geothermal steam 19, atemperature of the third feed water 36 is lower than the temperature ofthe geothermal steam 19. However, since a heat of the hot water 20,which is thrown away in the technique shown in FIG. 16, is recovered inthis embodiment, a heat recovery quantity from the geothermal steam 19is larger. In addition, according to this embodiment, since all thesteam constitutes the Rankine cycle of a high temperature and a highpressure, an efficiency according to this embodiment is equal to thetechnique shown in FIG. 14. As compared with a case in which thetechnique shown in FIG. 14 and the technique shown in FIG. 15 separatelyexist, an output of this embodiment is large and an efficiency is higheven if the received heat quantity is the same. Further, the receivedheat quantity in Example 2 is larger. Thus, a highly efficient powergeneration can be carried out by using the geothermal steam from which ahighly efficient power generation was impossible. Since the operation ofthe gas turbine is not influenced, there is no possibility that a powergeneration output and an efficiency of the gas turbine are degraded.

The structure shown in FIG. 2 is nothing more than an example, and themerging point 34 at which the second feed water 35 and the third feedwater 36 merge with each other may not the middle location of theexhaust heat boiler 15, but may be a location that is downstream of theoutlet thereof.

An effect of this embodiment is described with reference to FIG. 19. Asshown in FIG. 19( a), a feed water is heated from a condensationtemperature to a steam turbine inlet temperature in the followingmanner. The feed water of a lower temperature zone is heated by theexhaust heat boiler 15 using the heat source derived from a fossil fuel(first heat source) and the geothermal steam which is the heat sourceother than a fossil fuel (third heat source). The feed water of a highertemperature zone is heated by the exhaust heat boiler 15 using the heatsource derived from a fossil fuel (first heat source).

In this manner, since the feed water of the lower temperature zone isheated also by the geothermal steam, and a high temperature steamflowing into the steam turbine 1 is reliably generated by the exhaustheat boiler 15 derived from a fossil fuel, the geothermal steam of alower temperature, which has not been used heretofore in the steamturbine 1, can be efficiently used to improve a power generationefficiency.

Third Embodiment

Next, the steam turbine plant according to a third embodiment isdescribed with reference to FIG. 3.

In the steam turbine plant shown in FIG. 3, the same part as that of thesteam turbine plant shown in FIG. 1 is shown by the same referencenumber and detailed description thereof is omitted.

As shown in FIG. 3, there is installed a heater 47. In FIG. 3, theheater 47 is configured to heat a third feed water 36 by a heat recoverywater (third heat source) 40 which recovers an industrial exhaust heat.The industrial exhaust heat is an exhaust heat generated from a factoryor an office building. In general, the industrial heat is recovered bythe heat recovery water 40 that circulates up to a cooling water, and isreleased to an atmospheric air from the cooling tower. The heat recoverywater 40 is caused to circulate, not through the cooling tower, butthrough the heater 47. The heat recovery water 40, which recovers heatfrom an industrial exhaust heat source 39, is circulated by a recoverywater pump 41. A temperature of the heat recovery water 40 upon recoveryof the industrial exhaust heat is lower, as a circulation flow ratethereof is larger. It is preferable that the flow rate of the heatrecovery water 40 is higher than a flow rate of a feed water 42. Since apressure of the heat recovery water 40, which is a pressure for ahigh-temperature high-pressure turbine, is high, the heat recovery water40 is not generally heated to a temperature as a boiling point at itspressure. The third feed water 36 flows into the heater 47, and isheated by the heat recovery water 40 so as to have a higher temperature.After that, the third feed water 36 flows into a middle location of anexhaust heat boiler 15, and merges with a second feed water 35, whichhas been heated by the exhaust heat boiler 15. It is preferable that themerging point 34 is located such that a temperature of the second feedwater 35 and a temperature of the third feed water 36 are substantiallyequal to each other, but it is not a must.

A heat quantity of the industrial steam may considerably vary, but aproperty of the steam 2 flowing into the steam turbine 1 should notconsiderably vary. In a general steam turbine plant, a temperature and apressure of the steam 2 are measured, and the temperature and thepressure should not considerably vary. In a general steam turbine plant,a flow rate of the steam 2 is obtained by measuring a flow rate of thewater 42, for example, and the flow rate of the steam 2 should notconsiderably vary.

For this reason, it is preferable that an output of the feed pump 6 isadjusted so as to adjust a flow rate and a pressure of the feed water42, that a flow rate ratio between the second feed water 35 and thethird feed water 36 is adjusted by adjusting opening degrees of thevalves 37 and 38, and that, depending on cases, a flow rate of the heatrecovery water 40 is increased or decreased by adjusting an output ofthe recovery pump water 41, in order that the temperature, the pressureand the flow rate of the steam 2 do not considerably vary. At this time,although not shown, a flow-rate adjusting valve may be installed on adownstream of the feed pump 6, so as to adjust the flow rate and thepressure of the feed water 42 by adjusting an opening degree of theflow-rate adjusting valve. The merged water is heated by the exhaustheat boiler 15 so as to change to the steam 2. Then, the steam 2 flowsinto the steam turbine 1. In FIG. 18, the water is heated in parallel bytwo kinds of heat sources from b to n, and is heated by one kind of heatsource from n to i. When the third feed water 36 is not circulatedthrough a heater 47 for some reason or other, the valves 37 and 38 aretotally closed. Since a flow rate of the third feed water 36 issufficiently smaller than a flow rate of the second feed water 35, evenif the flow rate of the steam 2 somewhat lowers, the steam turbine 1 canbe operated.

According to this embodiment, when an outlet temperature of the gasturbine exhaust gas 14 of the exhaust gas boiler 15 is equal to thetechnique shown in FIG. 14, a received heat quantity from the exhaustgas boiler 15 is equal to the technique shown in FIG. 14. Thus, as theRankine cycle, a received heat quantity is increased by a heat receivedfrom the heat recovery water 40, so that a flow rate of the steam 2 isincreased to increase an output, while a steam turbine inlet temperatureis unchanged. An efficiency of the Rankine cycle is determined only bythe area ratio in the TS line diagram, regardless of a flow rate. Inaddition, according to this embodiment, since all the steam constitutesthe Rankine cycle of a high temperature and a high pressure, anefficiency according to this embodiment is equal to the technique shownin FIG. 14. Moreover, according to this embodiment, a highly efficientpower generation can be carried out by using the industrial exhaust heatwhich is discharged without being efficiently used. Since the operationof the gas turbine is not influenced, there is no possibility that apower generation output and an efficiency of the gas turbine aredegraded.

An effect of this embodiment is described with reference to FIG. 19. Asshown in FIG. 19( a), a feed water is heated from a condensationtemperature to a steam turbine inlet temperature in the followingmanner. The feed water of a lower temperature zone is heated by theexhaust heat boiler 15 using the heat source derived from a fossil fuel(first heat source) and the heat recovery water which is the heat sourceother than a fossil fuel (third heat source). The feed water of a highertemperature zone is heated by the exhaust heat boiler 15 using the heatsource derived from a fossil fuel (first heat source).

In this manner, since the feed water of the lower temperature zone isheated also by the heat recovery water, and a high temperature steamflowing into the steam turbine 1 is reliably generated by the exhaustheat boiler 15 derived from a fossil fuel, the heat recovery water of alower temperature, which has not been used heretofore in the steamturbine 1, can be efficiently used to improve a power generationefficiency.

Fourth Embodiment

Next, the steam turbine plant according to a fourth embodiment isdescribed with reference to FIG. 3.

In the third embodiment, the heat recovery water (third heat source) 40recovers the industrial exhaust heat. On the other hand, in the fourthembodiment, the heat recovery water 40 recovers all or a part of anexhaust heat of a fuel battery 46. As shown in FIG. 3, when the fuelbattery 46 generates power by using a fossil fuel, a large amount ofexhaust heat is generated. The exhaust heat of the large-sized fuelbattery 46, which generates power of a large capacity, is recovered bythe heat recovery water 40. In general, the heat recovery water 40 isvariously used so that a temperature thereof lowers, and the heatrecovery water 40 is finally released to an atmospheric air from acooling tower so as to be circulated. The heat recovery water 40 iscaused to circulate, not through the cooling tower, but through a heater47. At this time, the heat recovery water 40 may not be variously usedbut may be caused to circulate directly through the heater 47. Atemperature of the heat recovery water 40 upon recovery of theindustrial exhaust heat is lower, as a circulation flow rate thereof islarger. It is preferable that the flow rate of the heat recovery water40 is higher than a flow rate of a feed water 42. Since a pressure ofthe heat recovery water 40, which is a pressure for a high-temperaturehigh-pressure turbine, is high, the heat recovery water 40 is notgenerally heated to a temperature as a boiling point at its pressure. Aheat quantity of the exhaust heat of the fuel battery 46 may varydepending on an operation of the fuel battery 46, but a property of asteam 2 flowing into a steam turbine 1 should not considerably vary. Ina general steam turbine plant, a temperature and a pressure of the steam2 are measured, and the temperature and the pressure should notconsiderably vary. In a general steam turbine plant, a flow rate of thesteam is obtained by measuring a flow rate of the water 42, for example,and the flow rate of the steam 2 should not considerably vary. For thisreason, it is preferable that an output of the feed pump 6 is adjustedso as to adjust a flow rate and a pressure of the feed water 42, that aflow rate ratio between a second feed water 35 and a third feed water 36is adjusted by adjusting opening degrees of valves 37 and 38, and that,depending on cases, a flow rate of the heat recovery water 40 isincreased or decreased by adjusting an output of a recovery water pump41, in order that the temperature, the pressure and the flow rate of thesteam 2 do not considerably vary. At this time, although not shown, aflow-rate adjusting valve may be installed on a downstream of the feedpump 6, so as to adjust the flow rate and the pressure of the feed water42 by adjusting an opening degree of the flow-rate adjusting valve.

Similarly to the third embodiment, a highly efficient power generationcan be carried out by using all or a part of the exhaust heat of thefuel battery 46 which is discharged without being efficiently used.Since the operation of the gas turbine is not influenced, there is nopossibility that a power generation output and an efficiency of the gasturbine are degraded.

Fifth Embodiment

Next, the steam turbine plant according to a fifth embodiment isdescribed with reference to FIG. 4.

In the steam turbine plant shown in FIG. 4, the same part as that of thesteam turbine plant shown in FIG. 3 is shown by the same referencenumber and detailed description thereof is omitted.

As shown in FIG. 4, a heater 47 is installed. In FIG. 5, the heater 47is a heater configured to heat a steam 2 by a heat recovery water 40that recovers an industrial exhaust heat. A feed water 42 is transportedto the heater 47, and is heated by the heat recover water (third heatsource) 40 so as to have a higher temperature. The feed water 42 flowingout from the heater 47 flows into an exhaust heat boiler 15. The feedwater 42 is heated by a gas turbine exhaust gas 14 so as to change to asteam 2.

When the gas turbine exhaust gas 14 heats the feed water 42, atemperature thereof lowers. However, a surface temperature of a metal ofthe exhaust heat boiler 15 in contact with the gas turbine exhaust gas14 should not lower down to a low temperature corrosion temperaturezone. Depending on a composition of a natural gas or a town gas, thetemperature is 150° C., for example. If a temperature of the industrialexhaust heat is higher than the temperature, when the exhaust heatboiler 15 and the heater 47 are connected in series with respect to thefeed water 42, a temperature of the gas turbine exhaust gas 14 does notlower down to the temperature of the feed water 42 at an outlet of theheater 47. Thus, a heat cannot be received from the gas turbine exhaustgas 14 subsequently. However, since the temperature of the industrialexhaust heat is generally lower than the low temperature corrosiontemperature zone, there is no possibility that a heat received from thegas turbine exhaust gas 14 decreases. Since the industrial exhaust heathas a relatively lower temperature but an amount thereof is large, it ispreferable that heat is exchanged between the industrial exhaust heatand the feed water 42, while a temperature difference between theindustrial exhaust heat and the feed water 42 is sufficientlymaintained. The arrangement of the heater 47 is effective in termsthereof.

A heat quantity of the industrial exhaust heat may considerably vary,but a property of the steam 2 flowing into the steam turbine 1 shouldnot considerably vary. In a general steam turbine plant, a temperatureand a pressure of the steam 2 are measured, and the temperature and thepressure should not considerably vary. In a general steam turbine plant,a flow rate of the steam is obtained by measuring a flow rate of thewater 42, for example, and the flow rate of the steam 2 should notconsiderably vary. For this reason, it is preferable that an output ofthe feed pump 6 is adjusted so as to adjust the flow rate and thepressure of the feed water 42, and that, depending on cases, a flow rateof the heat recovery water 40 is increased or decreased by adjusting anoutput of a recovery water pump 41, in order that the temperature, thepressure and the flow rate of the steam 2 do not considerably vary. Atthis time, although not shown, a flow-rate adjusting valve may beinstalled on a downstream of the feed pump 6, so as to adjust the flowrate and the pressure of the feed water 42 by adjusting an openingdegree of the flow-rate adjusting valve.

Although the industrial exhaust heat is used in this embodiment, a heatto be used is not limited thereto. In addition, the number of the feedwater heaters 9 may be one.

Sixth Embodiment

Next, the steam turbine plant according to a sixth embodiment isdescribed with reference to FIG. 5.

In the steam turbine plant shown in FIG. 5, the same part as that of thesteam turbine plant shown in FIG. 1 is shown by the same referencenumber and detailed description thereof is omitted.

As shown in FIG. 5, a waste boiler 18 is installed as a heater. A feedwater 42 is diverged into a second feed water 35 and the third feedwater 36. The second feed water 35 is transported to a group of one ormore feed water heaters 9 (two in FIG. 5) that are connected in series.The second feed water 35 is heated therein by an extracted steam 8 tohave a higher temperature. The third feed water 36 flows into the wasteboiler 18 as a heater 47, and is heated by a waste exhaust combustiongas 44 so as to have a higher temperature.

Since a pressure of the third feed water 36, which is equal to apressure of the second feed water 35 for a high-temperaturehigh-pressure turbine, is higher than a pressure in a waste powergeneration, the third feed water 36 does not basically boil. Thus, thewaste boiler 18 functions only as a hot water boiler. Thereafter, thethird feed water 36 flows into an outlet or a middle location of thegroup of the feed water heaters 9, and merges with the second feed water35 which has been heated by the feed water heater 9 disposed on anupstream thereof.

A temperature of the third feed water 36 is restricted in terms of hightemperature corrosion. It is preferable that the merging point 34 islocated such that the temperature of the second feed water 35 and thetemperature of the third feed water 36 are substantially equal to eachother, but it is not a must.

In the waste boiler 18, a composition of the waste 11 and an amount ofthe waste 11 to be treated may considerably vary, but a property of thesteam 2 flowing into the steam turbine 1 should not considerably vary.In a general steam turbine plant, a temperature and a pressure of thesteam 2 are measured, and the temperature and the pressure should notconsiderably vary. In addition, in a general steam turbine plant, a flowrate of the steam 2 is obtained by measuring a flow rate of the feedwater 42, for example, and the flow rate of the steam 2 should notconsiderably vary. For this reason, an output of the feed pump 6 isadjusted so as to adjust a flow rate and a pressure of the feed water42, and a flow rate ratio between the second feed water 35 and the thirdfeed water 36 is adjusted by adjusting opening degrees of valves 37 and38, in order that the temperature, the pressure and the flow rate of thesteam 2 do not considerably vary. In addition, it is preferable that anoutput of a coal fired boiler 7 is increased or decreased, and that,depending on cases, an amount the waste 11 to be treated is increased ordecreased. At this time, although not shown, a flow-rate adjusting valvemay be installed on a downstream of the feed pump 6, so as to adjust theflow rate and the pressure of the feed water 42 by adjusting an openingdegree of the flow-rate adjusting valve.

A pressure of the third feed water 36, which is a working fluid of thewaste boiler, is adjusted by the feed pump 6. The pressure of the thirdfeed water 36 is a pressure for a high-temperature high-pressure turbinesimilarly to the technique shown in FIG. 14. Thus, the pressure of thethird feed water 36 is higher than a pressure of the technique shown inFIG. 15. In FIG. 18, the merging point 34 is shown by 1. If there is thefeed water heater 9 downstream of the merging point 34, the merged wateris heated by the same. After that, the merged water flows into the coalfired boiler 7, and is heated by the coal fired boiler 7 so as to changeto a steam 2. Then, the steam 2 flows into the steam turbine 1. When thethird feed water 36 is not circulated for some reason or other, thevalves 37 and 38 are totally closed. Since a flow rate of the third feedwater 36 is sufficiently smaller than a flow rate of the second feedwater 35, even if the flow rate of the steam 2 somewhat lowers, thesteam turbine 1 can be operated.

Similarly to the embodiment shown in FIG. 1, since all the steamconstitutes the Rankine cycle of a high temperature and a high pressure,an efficiency according to this embodiment is equal to the techniqueshown in FIG. 13. In addition, as compared with a case in which thetechnique shown in FIG. 13 and the technique shown in FIG. 15 separatelyexist, an output of this embodiment is large and an efficiency is higheven if the same received heat quantity is generated. Thus, a highlyefficient power generation can be carried out by using the heat from thewaste boiler 18 which from which a highly efficient power generation wasimpossible.

The structure shown in FIG. 5 is nothing more than an example, and themerging point 34 at which the second feed water 35 and the third feedwater 36 merge with each other may not be located between the mostdownstream feed water heater and the coal fired boiler 7, but may be amiddle location of the group of two or more feed water heaters 9.Namely, the feed water heater may be provided downstream of the mergingpoint 34. In addition, the number of the feed water heaters 9 may beone.

Further, the one or more feed water heaters 9 may be disposed not onlyon an upstream side of the diverging point of the second feed water 35and the third feed water 36, but also on a downstream side thereof.

Seventh Embodiment

Next, the steam turbine plant according to a seventh embodiment isdescribed with reference to FIG. 6.

In the steam turbine plant shown in FIG. 6, the same part as that of thesteam turbine plant shown in FIG. 5 is shown by the same referencenumber and detailed description thereof is omitted.

As shown in FIG. 6, there is installed a heater 47 configured to heat asteam 2 by a geothermal steam 19. According to this embodiment, thegeothermal steam 19 (third heat source) directly flows into the heater47. A third feed water 36 flows into the heater 47, and is heated by thegeothermal steam 19 so as to have a higher temperature. Since a pressureof the third feed water 36 is equal to a pressure of a second feed water35 for a high-temperature high-pressure turbine, the third feed water 36does not basically boil. Thereafter, the third feed water 36 flows intoan outlet or a middle location of a group of feed water heaters 9, andmerges with the second feed water 35 which has been heated by the feedwater heater 9 disposed on an upstream thereof. A temperature of thethird feed water 36 does not raise up to a temperature of the geothermalsteam 19. It is preferable that the merging point 34 is located suchthat the temperature of the second feed water 35 and the temperature ofthe third feed water 36 are substantially equal to each other, but it isnot a must.

A flow rate and a temperature of the geothermal steam 19 mayconsiderably vary, but a property of the steam 2 flowing into a steamturbine 1 should not considerably vary. In a general steam turbineplant, a temperature and a pressure of the steam 2 are measured, and thetemperature and the pressure should not considerably vary. In a generalsteam turbine plant, a flow rate of the steam is obtained by measuring aflow rate of a water 42, for example, and the flow rate of the steam 2should not considerably vary. For this reason, an output of the feedpump 6 is adjusted so as to adjust a flow rate and a pressure of thefeed water 42, a flow rate ratio between the second feed water 35 andthe third feed water 36 is adjusted by adjusting opening degrees ofvalves 37 and 38, in order that the temperature, the pressure and theflow rate of the steam 2 do not considerably vary. At this time,although not shown, a flow-rate adjusting valve may be installed on adownstream of the feed pump 6, so as to adjust the flow rate and thepressure of the feed water 42 by adjusting an opening degree of theflow-rate adjuting valve. In addition, it is preferable that an outputof the coal fired boiler 7 is increased or decreased, and that,depending on cases, a flow rate of the geothermal steam 19 is increasedor decreased by a not-shown flow-rate adjusting valve. A pressure of thethird feed water 36, which is adjusted by the feed pump 6, is a pressurefor a high-temperature high-pressure turbine similarly to the techniqueshown in FIG. 13. Thus, the pressure of the third feed water 36 ishigher than a pressure of the geothermal steam 19 in the technique shownin FIG. 16. Therefore, the third feed water 36 does not boil evenpartially. A merging point 34 is shown by m in FIG. 18. If there is thefeed water heater 9 downstream of the merging point 34, the merged wateris heated by the same. After that, the merged water flows into the coalfired boiler 7, and is heated by the coal fired boiler 7 so as to changeto a steam 2. Then, the steam 2 flows into the steam turbine 1. When thethird feed water 36 is not circulated for some reason or other, thevalves 37 and 38 are totally closed. Since a flow rate of the third feedwater 36 is sufficiently smaller than a flow rate of the second feedwater 35, even if the flow rate of the steam 2 somewhat lowers, thesteam turbine 1 can be operated.

In the technique shown in FIG. 16, a temperature of the steam 2separated by a steam separator 45 is the same as a temperature of thegeothermal steam 19. On the other hand, according to this embodiment,since the third feed water 36 is heated by the geothermal steam 19, atemperature of the third feed water 36 is lower than the temperature ofthe geothermal steam 19. However, since a heat of the hot water 20,which is thrown away in the technique shown in FIG. 16, is recovered inthis embodiment, a heat recovery quantity from the geothermal steam 19is larger according to this embodiment. In addition, similar to theembodiment shown in FIG. 5, since all the steam constitutes the Rankinecycle of a high temperature and a high pressure, an efficiency accordingto this embodiment is equal to the technique shown in FIG. 13. Inaddition, as compared with a case in which the technique shown in FIG.13 and the technique shown in FIG. 15 separately exist, an output ofthis embodiment is large and an efficiency is high even if the samereceived heat quantity is generated. Thus, a highly efficient powergeneration can be carried out by using the heat from the waste boiler 18from which a highly efficient power generation was impossible.

The structure shown in FIG. 6 is nothing more than an example, and themerging point 34 at which the second feed water 35 and the third feedwater 36 merge with each other may not be located between the mostdownstream feed water heater and the coal fired boiler 7, but may be amiddle location of the group of two or more feed water heaters 9.Namely, the feed water heater may be provided downstream of the mergingpoint 34. In addition, the number of the feed water heaters 9 may beone.

Further, the one or more feed water heaters 9 may be disposed not onlyon an upstream side of the diverging point of the second feed water 35and the third feed water 36, but also on a downstream side thereof.

Eighth Embodiment

Next, the steam turbine plant according to an eighth embodiment isdescribed with reference to FIG. 7.

In the steam turbine plant shown in FIG. 7, the same part as that of thesteam turbine plant shown in FIG. 5 is shown by the same referencenumber and detailed description thereof is omitted.

As shown in FIG. 7, a heater 47 is installed. The heater 47 shown inFIG. 7 is the heater 47 configured to heat a third feed water 36 by aheat recovery water (third heat source) 40 which recovers an industrialexhaust heat. A temperature of the heat recovery water 40 upon recoveryof the industrial exhaust heat is lower, as a circulation flow ratethereof is larger. It is preferable that the flow rate of the heatrecovery water 40 is higher than a flow rate of a feed water 42. Thethird feed water 36 flows into the heater 47, and is heated by the heatrecovery water 40 so as to have a higher temperature. After that, thethird feed water 36 flows into an outlet or a middle location of a groupof feed water heaters 9, and merges with a second feed water 35, whichhas been heated by the feed water heater 9 disposed on an upstreamthereof. A temperature of the third feed water 36 does not raise up to atemperature of the geothermal steam 19. It is preferable that themerging point 34 is located such that the temperature of the second feedwater 35 and the temperature of the third feed water 36 aresubstantially equal to each other, but it is not a must.

A heat quantity of the industrial steam may considerably vary, but aproperty of the steam 2 flowing into the steam turbine 1 should notconsiderably vary. In a general steam turbine plant, a temperature and apressure of the steam 2 are measured, and the temperature and thepressure should not considerably vary. In a general steam turbine plant,a flow rate of the steam is obtained by measuring a flow rate of thewater 42, for example, and the flow rate of the steam 2 should notconsiderably vary.

For this reason, an output of the feed pump 6 is adjusted so as toadjust a flow rate and a pressure of the feed water 42, and a flow rateratio between the second feed water 35 and the third feed water 36 isadjusted by adjusting opening degrees of valves 37 and 38, in order thatthe temperature, the pressure and the flow rate of the steam 2 do notconsiderably vary. In addition, it is preferable that an output of acoal fired boiler 7 is increased or decreased, and that, depending oncases, a flow rate of the heat recovery water 40 may be increased ordecreased by adjusting an output of a recovery water pump 41. At thistime, although not shown, a flow-rate adjusting valve may be installedon a downstream of the feed pump 6, so as to adjust the flow rate andthe pressure of the feed water 42 by adjusting an opening degree of theflow-rate adjusting valve.

As shown in FIG. 7, if there is the feed water heater 9 downstream of amerging point 34, a merged water is heated by the same. After that, themerged water flows into the coal fired boiler 7, and is heated by thecoal fired boiler 7 so as to change to a steam 2. Then, the steam 2flows into the steam turbine 1. In FIG. 18, the water is heated inparallel by two kinds of heat sources from b to n, and is heated by onekind of heat source from n to i. When the third feed water 36 is notcirculated through the heater 47 for some reason or other, the valves 37and 38 are totally closed. In general, since a steam flow rate in thewaste power generation is sufficiently smaller than a steam flow rate inthe combined cycle, even if the flow rate of the steam 2 somewhatlowers, the steam turbine 1 can be operated.

As the Rankine cycle, a received heat quantity is increased by a heatreceived from the heat recovery water 40, so that a flow rate of thesteam 2 is increased to increase an output, while a steam turbine inlettemperature is unchanged. An efficiency of the Rankine cycle isdetermined only by the area ratio in the TS line diagram, regardless ofa flow rate. Although a temperature difference between an extractedsteam 8 and the second feed water 35 slightly varies, all the steamconstitutes the Rankine cycle of a high temperature and a high pressure.Thus, an efficiency according to the eighth embodiment is equal to thefirst conventional technique. A highly efficient power generation can becarried out by using the industrial exhaust heat discharged withoutbeing efficiently used.

The structure shown in FIG. 7 is nothing more than an example, and themerging point 34 at which the second feed water 35 and the third feedwater 36 merge with each other may not be a middle location of the groupof two or more feed water heaters 9, but may be located between the mostdownstream feed water heater and the coal fired boiler 7. In addition,the number of the feed water heaters 9 may be one.

Further, the one or more feed water heaters 9 may be disposed not onlyon an upstream side of the diverging point of the second feed water 35and the third feed water 36, but also on a downstream side thereof.

Ninth Embodiment

Next, the steam turbine plant according to a ninth embodiment isdescribed with reference to FIG. 7.

In the eighth embodiment, the heat recovery water 40 recovers theindustrial exhaust heat. On the other hand, in this embodiment, the heatrecovery water 40 recovers all or a part of an exhaust heat of a fuelbattery or an internal combustion engine 46. Herein, the internalcombustion engine means a gas engine or a diesel engine, for example.When the fuel battery or the internal combustion engine 46 generatespower by using a fossil fuel, a large amount of exhaust heat isgenerated. The exhaust heat of the large-sized fuel battery or thelarge-sized internal combustion engine 46, which generates power of alarge capacity, is recovered by the heat recovery water 40. In general,the heat recovery water 40 is variously used so that a temperaturethereof lowers, and the heat recovery water 40 is finally released to anatmospheric air from a cooling tower so as to be circulated. The heatrecovery water 40 is caused to circulate, not through the cooling tower,but through the heater 47. At this time, the heat recovery water 40 maynot be variously used but may be caused to circulate directly throughthe heater 47. A temperature of the heat recovery water 40 upon recoveryof the industrial exhaust heat is lower, as a circulation flow ratethereof is larger. It is preferable that the flow rate of the heatrecovery water 40 is higher than a flow rate of a feed water 42. Since apressure of the heat recovery water 40, which is a pressure for ahigh-temperature high-pressure turbine, is high, the heat recovery water40 is not generally heated to a temperature as a boiling point at itspressure. A heat quantity of the exhaust heat of the fuel battery or theinternal combustion engine 46 may vary depending on an operation of thefuel battery or the internal combustion engine 46, but a property of thesteam 2 flowing into the steam turbine 1 should not considerably vary.In a general steam turbine plant, a temperature and a pressure of thesteam 2 are measured, and the temperature and the pressure should notconsiderably vary. In a general steam turbine plant, a flow rate of thesteam is obtained by measuring a flow rate of the water 42, for example,and the flow rate of the steam 2 should not considerably vary.

For this reason, an output of the feed pump 6 is adjusted so as toadjust a flow rate and a pressure of the feed water 42, and a flow rateratio between a second feed water 35 and a third feed water 36 isadjusted by adjusting opening degrees of valves 37 and 38, in order thatthe temperature, the pressure and the flow rate of the steam 2 do notconsiderably vary. In addition, it is preferable that an output of acoal fired boiler 7 is increased or decreased, and that, depending oncases, a flow rate of the heat recovery water 40 is increased ordecreased by adjusting an output of a recovery water pump 41. At thistime, although not shown, a flow-rate adjusting valve may be installedon a downstream of a feed pump 6, so as to adjust the flow rate and thepressure of the feed water 42 by adjusting an opening degree of theflow-rate adjusting valve.

According to this embodiment, a highly efficient power generation can becarried out by using all or a part of the exhaust heat of the fuelbattery 46 which is discharged without being efficiently used.

The structure shown in FIG. 7 is nothing more than an example, and themerging point 34 at which the second feed water 35 and the third feedwater 36 merge with each other may not be a middle location of the groupof two or more feed water heaters 9, but may be located between the mostdownstream feed water heater and the coal fired boiler 7. In addition,the number of the feed water heaters 9 may be one.

Further, the one or more feed water heaters 9 may be disposed not onlyon an upstream side of the diverging point of the second feed water 35and the third feed water 36, but also on a downstream side thereof.

Tenth Embodiment

Next, the steam turbine plant according to a tenth embodiment isdescribed with reference to FIG. 8.

In the steam turbine plant shown in FIG. 8, the same part as that of thesteam turbine plant shown in FIG. 7 is shown by the same referencenumber and detailed description thereof is omitted.

As shown in FIG. 8, a heater 47 is disposed in series with a group offeed water heaters 9 with respect to a feed water 42. In thisembodiment, the heater 47 is configured to heat the feed water 42 by aheat recovery water 40 which recovers an industrial exhaust heat. Thefeed water 42 is transported to the heater 47, and is heated therein bythe heat recovery water 40 so as to have a higher temperature. The feedwater 42 flowing out from the heater 47 sequentially flows into thegroup of feed water heaters 9 and a coal fired boiler 7, and is heatedrespectively by an extracted steam 8 and an exhaust combustion gas 13,so as to become a steam 2.

Since the industrial exhaust heat has a relatively lower temperature butan amount thereof is large, it is preferable that heat is exchangedbetween the industrial exhaust heat and the feed water 42, while atemperature difference between the industrial exhaust heat and the feedwater 42 is sufficiently maintained. The arrangement of the heater iseffective in terms thereof.

A heat quantity of the industrial exhaust heat may considerably vary,but a property of the steam 2 flowing into the steam turbine 1 shouldnot considerably vary. In a general steam turbine plant, a temperatureand a pressure of the steam 2 are measured, and the temperature and thepressure should not considerably vary. In a general steam turbine plant,a flow rate of the steam is obtained by measuring a flow rate of thewater 42, for example, and the flow rate of the steam 2 should notconsiderably vary. For this reason, it is preferable that an output ofthe feed pump 6 is adjusted so as to adjust a flow rate and a pressureof the feed water 42, that an output of the coal fired boiler isincreased or decreased, and that, depending on cases, a flow rate of theheat recovery water 40 is increased or decreased by adjusting an outputof a recovery water pump 41, in order that the temperature, the pressureand the flow rate of the steam 2 do not considerably vary. At this time,although not shown, a flow-rate adjusting valve may be installed on adownstream of the feed pump 6, so as to adjust the flow rate and thepressure of the feed water 42 by adjusting an opening degree of theflow-rate adjusting valve.

Although the industrial exhaust heat is used in the tenth embodiment, aheat to be used is not limited thereto.

In addition, the heater 47 may be disposed on a middle location of thegroup of two or more feed water heaters 9, or may be disposed on adownstream side of the group of the feed water heaters 9.

Further, the one or more feed water heaters 9 may be disposed not onlyon an upstream side of the diverging point of the second feed water 35and the third feed water 36, but also on a downstream side thereof.

Eleventh Embodiment

Next, the steam turbine plant according to an eleventh embodiment isdescribed with reference to FIG. 9.

In the steam turbine plant shown in FIG. 9, the same part as that of thesteam turbine plant shown in FIG. 8 is shown by the same referencenumber and detailed description thereof is omitted.

As shown in FIG. 9, a waste boiler 18 is installed as a heater. In FIG.9, no air is extracted from a steam turbine 1, and no feed water heater9 is included. A feed water 42 flows into the waste boiler 18 as aheater, and is heated by a waste exhaust combustion gas 44 so as to havea higher temperature. A temperature of an outlet water of the wasteboiler 18 is restricted in terms of a high temperature corrosion. Sincea pressure of the outlet water is higher than a pressure in a wastepower generation, the outlet water does not basically boil. Thus, thewaste boiler 18 functions only as a hot water boiler.

A pressure of a working fluid of the waste boiler 18, which is adjustedby a pump, is a pressure for a high-temperature high-pressure turbinesimilarly to the technique shown in FIG. 14. Thus, the pressure of theworking fluid of the waste boiler 18 is higher than that in thetechnique shown in FIG. 15. In FIG. 18, an outlet of the waste boiler 18is shown by 1.

Thereafter, the feed water 42 flows into a coal fired boiler 7, and isheated by the coal fired boiler 7. Then, the feed water 42 flows intothe steam turbine 1. In the waste boiler 18, a composition of the waste11 and an amount of the waste 11 to be treated may considerably vary,but a property of the steam 2 flowing into the steam turbine 1 shouldnot considerably vary. In a general steam turbine plant, a temperatureand a pressure of the steam 2 are measured, and the temperature and thepressure should not considerably vary. In addition, in a general steamturbine plant, a flow rate of the steam 2 is obtained by measuring aflow rate of the feed water 42, for example, and the flow rate of thesteam 2 should not considerably vary.

For this reason, it is preferable that an output of the feed pump 6 isadjusted so as to adjust a flow rate and a pressure of the feed water42, that an output of the coal fired boiler 7 is increased or decreased,and that, depending on cases, an amount of the waste 11 to be treated isincreased or decreased, in order that the temperature, the pressure andthe flow rate of the steam 2 do not considerably vary. At this time,although not shown, a flow-rate adjusting valve may be installed on adownstream of the feed pump 6, so as to adjust the flow rate and thepressure of the feed water 42 by adjusting an opening degree of theflow-rate adjusting valve.

Similarly to the embodiment shown in FIG. 8, since all the steamconstitutes the Rankine cycle of a high temperature and a high pressure,an efficiency according to this embodiment is equal to the techniqueshown in FIG. 13. This embodiment can be applied to the steam turbine 1which does not extract air.

Although the waste boiler 18 is used as a heater in the eleventhembodiment, a water may be heated by using a heat derived from anotherheat source.

Twelfth Embodiment

Next, the steam turbine plant according to a twelfth embodiment isdescribed with reference to FIG. 10.

In the steam turbine plant shown in FIG. 10, the same part as that ofthe steam turbine plant shown in FIG. 1 is shown by the same referencenumber and detailed description thereof is omitted.

As shown in FIG. 10, a heating medium 24 (fourth heat source) receives aradiant heat of solar light so as to be heated in a solar heat collector23. The heated heating medium 24 is diverged into two. One heatingmedium flows into a solar heat heater 22, and the other heating mediumflows into a heat storage tank 25. A heating medium pump 27 is adjustedsuch that the heating medium flows in a direction drawn by a solid lineon the left side of the heat storage tank 25. A part of the heatingmedium 24 flows into the solar heat heater to heat a feed water 42 tolose its temperature, and flows out therefrom. When a remaining part ofthe heating medium 24, which has heated the feed water 42, flows intothe heat storage tank 25, the heating medium, which has been alreadytherein and has a lower temperature, flows out from the heat storagetank 25, so that the heating medium 24 of a higher temperature is storedin the heat storage tank 25 in the end. After the heating medium 24 hasbeen stored, valves 30 and 31 are totally closed. The heating medium 24is transported by heating medium pumps 26 and 27. The feed water 42 istransported to the solar heat heater by a feed pump 6, and is heatedtherein so as to change to a steam 2. During a nighttime when no solarlight exists or a time zone when only weak solar light exists, valves 28and 29 are closed and the heating medium pump 26 is stopped, while thevalves 30 and 31 are opened and the heating medium pump 27 is operated,so that the heating medium flows in a direction drawn by dotted lines onthe right side of the heat storage tank 25. The feed water 24 is heatedby circulating the heating medium 24 between the heat storage tank 25and the solar heat heater 22, without circulating the heating medium 24through the solar heat collector 23. The feed water 42 heated by thesolar heat is sent to a steam turbine 1 so as to drive the steam turbine1.

As described above, the steam turbine 1 is a turbine that is driven by asteam manufactured by a heat source derived from solar heat (fourth heatsource). In the steam turbine 1, there is installed a heater 47, whichis configured to heat a third feed water 36 by a heat recovery water(fifth heat source) 40 that recovers an industrial exhaust heat. Atemperature of the heat recovery water 40 upon recovery of theindustrial exhaust heat is lower, as a circulation flow rate thereof islarger. It is preferable that the flow rate of the heat recovery water40 is higher than a flow rate of a feed water 42. Since a pressure ofthe heat recovery water 40, which is a pressure for a high-temperaturehigh-pressure turbine, is high, the heat recovery water 40 is notgenerally heated to a temperature as a boiling point at its pressure.When solar heat can be sufficiently obtained such as a daytime, thesteam turbine plant is operated in this manner.

The feed water 42 is diverged into the second feed water 35 and thethird feed water 36. The second feed water 35 is transported to a groupof feed water heaters 9, and is heated therein by an extracted steam 8so as to have a higher temperature. The third feed water 36 flows intothe heater 47, and is heated by the heat recovery water 40 so as to havea higher temperature. Thereafter, the third feed water 36 flows into amiddle location or a downstream of the group of the feed water heaters9, and merges with the second feed water 35 which has been heated by thefeed water heater 9 disposed on an upstream of a merging point 34.

It is preferable that the merging point 34 is located such that thetemperature of the second feed water 35 and the temperature of the thirdfeed water 36 are substantially equal to each other, but it is not amust. Both of a heat quantity of a solar heat and a heat quantity of anindustrial exhaust heat may considerably vary, but a property of thesteam 2 flowing into the steam turbine 1 should not considerably vary.In a general steam turbine plant, a temperature and a pressure of thesteam 2 are measured, and the temperature and the pressure should notconsiderably vary. In a general steam turbine plant, a flow rate of thesteam is obtained by measuring a flow rate of the water 42, for example,and the flow rate of the steam 2 should not considerably vary.

For this reason, it is preferable that flow rates of the heating mediumare increased or decreased by adjusting outputs of the heating mediumpumps 26 and 27, that an output of the feed pump 6 is adjusted so as toadjust a flow rate and a pressure of the feed water 42, that a flow rateratio between the second feed water 35 and the third feed water 36 isadjusted by adjusting opening degrees of the valves 37 and 38, and that,depending on cases, a flow rate of the heat recovery water 40 isincreased or decreased by adjusting an output of a recovery water pump41, in order that the temperature, the pressure and the flow rate of thesteam 2 do not considerably vary. At this time, although not shown, aflow-rate adjusting valve may be installed on a downstream of the feedpump 6, so as to adjust the flow rate and the pressure of the feed water42 by adjusting an opening degree of the flow-rate adjusting valve.

If there is the feed water heater 9 downstream of the merging point 34,the merged water is heated by the same. After that, the merged waterflows into the solar heat heater 22, and is heated by the solar heatheater 22 so as to change to a steam 2. Then, the steam 2 flows into thesteam turbine 1. When the third feed water 36 is not circulated throughthe heater 47 for some reason or other, the valves 37 and 38 are totallyclosed. Since a flow rate of the third feed water 36 is sufficientlysmaller than a flow rate of the second feed water 35, even if the flowrate of the steam 2 somewhat lowers, the steam turbine 1 can beoperated. During a nighttime when a solar heat is not obtained at ail oris obtained insufficiently, an operation similar to the fifthconventional technique is carried out.

As the Rankine cycle, a received heat quantity is increased by a heatreceived from the heat recovery water 40, so that a flow rate of thesteam 2 is increased to increase an output, while a steam turbine inlettemperature is unchanged. An efficiency of the Rankine cycle isdetermined only by the area ratio in the TS line diagram, regardless ofa flow rate. Since all the steam constitutes the Rankine cycle of a hightemperature and a high pressure, an efficiency according to the thisembodiment is equal to the technique shown in FIG. 17.

According to this embodiment, a power generation can be carried out,without lowering an efficiency from the technique shown in FIG. 17, byusing the industrial exhaust heat which is discharged without beingefficiently used.

The heat storage tank 25 may be omitted. However, in this case, thesteam turbine plant cannot be operated only when it can receive a solarheat sufficiently. The structure shown in FIG. 10 is nothing more thanan example, and the merging point 34 at which the second feed water 35and the third feed water 36 merge with each other may not be a middlelocation of the group of two or more feed water heaters 9, but may belocated between the most downstream feed water heater and the coal firedboiler 7. In addition, the number of the feed water heaters 9 may beone.

Further, the one or more feed water heaters 9 may be disposed not onlyon an upstream side of the diverging point of the second feed water 35and the third feed water 36, but also on a downstream side thereof. Inthis case, only one feed water heaters 9 may be provided.

An effect of this embodiment is described with reference to FIG. 19. Asshown in FIG. 19( b), a feed water is heated from a condensationtemperature to a steam turbine inlet temperature in the followingmanner. The feed water of a lower temperature zone is heated by a secondheating source using an extracted steam, and the heat recovery water 40which is a heat source other than a solar heat (fifth heat source). Thefeed water of a higher temperature zone is heated by the solar heatheater 22 using a heat source derived from a solar heat (fourth heatsource).

In this manner, since the feed water of the lower temperature zone isheated also by the heat recovery water, and a high temperature steamflowing into the steam turbine 1 is reliably generated by the solar heatheater 22 derived from a solar heat, the heat recovery water of a lowertemperature, which has not been used heretofore in the steam turbine 1,can be efficiently used to improve a power generation efficiency.

Thirteenth Embodiment

Next, the steam turbine plant according to a thirteenth embodiment isdescribed with reference to FIG. 10.

In the twelfth embodiment, the heat recovery water 40 recovers theindustrial exhaust heat. On the other hand, in this embodiment, the heatrecovery water 40 recovers all or a part of an exhaust heat of a fuelbattery or an internal combustion engine 46. When the fuel battery orthe internal combustion engine 46 generates power by using a fossilfuel, a large amount of exhaust heat is generated. The exhaust heat ofthe large-sized fuel battery or the large-sized internal combustionengine 46, which generates power of a large capacity, is recovered bythe heat recovery water 40. In general, the heat recovery water (fifthheat source) 40 is variously used so that a temperature thereof lowers,and the heat recovery water 40 is finally released to an atmospheric airfrom a cooling tower so as to be circulated. The heat recovery water 40is caused to circulate, not through the cooling tower, but through aheater 47. At this time, the heat recovery water 40 may not be variouslyused but may be caused to circulate directly through the heater 47. Atemperature of the heat recovery water 40 upon recovery of theindustrial exhaust heat is lower, as a circulation flow rate thereof islarger. It is preferable that the flow rate of the heat recovery water40 is higher than a flow rate of a feed water 42.

Since a pressure of the heat recovery water 40, which is a pressure fora high-temperature high-pressure turbine, is high, the heat recoverywater 40 is not generally heated to a temperature as a boiling point atits pressure. A heat quantity of solar heat may considerably vary, and aheat quantity of the exhaust heat of the fuel battery or the internalcombustion engine 46 may vary depending on an operation of the fuelbattery or the internal combustion engine 46, but a property of thesteam 2 flowing into the steam turbine 1 should not considerably vary.In a general steam turbine plant, a temperature and a pressure of thesteam 2 are measured, and the temperature and the pressure should notconsiderably vary. In a general steam turbine plant, a flow rate of thesteam is obtained by measuring a flow rate of a water 42, for example,and the flow rate of the steam 2 should not considerably vary.

For this reason, it is preferable that flow rates of the heating mediumare increased or decreased by adjusting outputs of heating medium pumps26 and 27, that an output of the feed pump 6 is adjusted so as to adjusta flow rate and a pressure of the feed water 42, that a flow rate ratiobetween the second feed water 35 and the third feed water 36 is adjustedby adjusting opening degrees of valves 37 and 38, and that, depending oncases, a flow rate of the heat recovery water 40 is increased ordecreased by adjusting an output of a recovery water pump 41, in orderthat the temperature, the pressure and the flow rate of the steam 2 donot considerably vary. At this time, although not shown, a flow-rateadjusting valve may be installed on a downstream of the feed pump 6, soas to adjust the flow rate and the pressure of the feed water 42 byadjusting an opening degree of the flow-rate adjusting valve.

According to this embodiment, a highly efficient power generation can becarried out by using all or a part of the exhaust heat of the fuelbattery 46 which is discharged without being efficiently used.

A heat storage tank 25 may be omitted. However, in this case, the steamturbine plant can be operated only when it can receive a solar heatsufficiently. The structure shown in FIG. 10 is nothing more than anexample, and the merging point 34 at which the second feed water 35 andthe third feed water 36 merge with each other may not be a middlelocation of the group of two or more feed water heaters 9, but may belocated between the most downstream feed water heater and the solar heatheater 22. In addition, the number of the feed water heaters 9 may beone.

Further, the one or more feed water heaters 9 may be disposed not onlyon an upstream side of the diverging point of the second feed water 35and the third feed water 36, but also on a downstream side thereof. Onlyone feed water heaters 9 may be provided.

Furthermore, although there is shown in FIG. 10 the example in which theheat recovery water 40 is heated by an exhaust heat source 39, or thefuel battery or the internal combustion engine 46, the present inventionis not limited thereto. The heat recovery water 40 may be heated by anexhaust gas of the gas turbine, and the heater 47 may be heated by theheat recovery water 40.

Fourteenth Embodiment

Next, the steam turbine plant according to a fourteenth embodiment isdescribed with reference to FIG. 11.

In the steam turbine plant shown in FIG. 11, the same part as that ofthe steam turbine plant shown in FIG. 10 is shown by the same referencenumber and detailed description thereof is omitted.

As shown in FIG. 11, a heater 47 is disposed in series with a solar heatheater 22 and a group of feed water heaters 9, with respect to a feedwater 42. As shown in FIG. 11, the heater 47 is configured to heat asteam 2 by a heat recovery water 40 which recovers an industrial exhaustheat. A feed water 42 is transported to the heater 47, and is heatedtherein by the heat recovery water 40 so as to have a highertemperature. The feed water 42 flowing out from the heater 47sequentially flows into the group of the feed water heaters 9 and thesolar heat heater 22, and is heated respectively by an extracted steam 9and a heating medium 24, so as to become a steam 2.

Since the industrial exhaust heat has a relatively lower temperature butan amount thereof is large, it is preferable that heat is exchangedbetween the industrial exhaust heat and the feed water 42, while atemperature difference between the industrial exhaust heat and the feedwater 42 is sufficiently maintained. The arrangement of the heater 47 iseffective in terms thereof.

Both of a heat quantity of a solar heat and a heat quantity of anindustrial exhaust heat may considerably vary, but a property of thesteam 2 flowing into the steam turbine 1 should not considerably vary.In a general steam turbine plant, a temperature and a pressure of thesteam 2 are measured, and the temperature and the pressure should notconsiderably vary. In a general steam turbine plant, a flow rate of thesteam is obtained by measuring a flow rate of the water 42, for example,and the flow rate of the steam 2 should not considerably vary.

For this reason, it is preferable that flow rates of the heating mediumare increased or decreased by adjusting outputs of heating medium pumps26 and 27, that an output of a feed pump is adjusted so as to adjust aflow rate and a pressure of the feed water 42, and that, depending oncases, a flow rate of the heat recovery water 40 is increased ordecreased by adjusting an output of a recovery water pump 41, in orderthat the temperature, the pressure and the flow rate of the steam 2 donot considerably vary. At this time, although not shown, a flow-rateadjusting valve may be installed on a downstream of the feed pump 6, soas to adjust the flow rate and the pressure of the feed water 42 byadjusting an opening degree of the flow-rate adjusting valve.

Although the industrial exhaust heat is used in this embodiment, a heatto be used is not limited thereto. In addition, similarly to theeleventh embodiment, a feed water heater may be omitted. Moreover, aheat storage tank 25 may be omitted. However, in this case, the steamturbine plant can be operated only when it can receive a solar heatsufficiently.

In addition, the heater 47 may be disposed on a middle location of thegroup of two or more feed water heaters 9, or may be disposed on adownstream side of the group of the feed water heaters 9.

Further, the one or more feed water heaters 9 may be disposed not onlyon an upstream side of the diverging point of the second feed water 35and the third feed water 36, but also on a downstream side thereof.

Fifteenth Embodiment

Next, the steam turbine plant according to a fifteenth embodiment isdescribed with reference to FIG. 12.

In the steam turbine plant shown in FIG. 12, the same part as that ofthe steam turbine plant shown in FIG. 10 is shown by the same referencenumber and detailed description thereof is omitted.

During a daytime or the like when a solar heat can be sufficientlyobtained, the steam turbine plant is operated in the following manner. Afeed water 42 is diverged into a second feed water 35 and a third feedwater 36. The second feed water 35 is transported to a solar heat heater22, and is heated therein so as to have a higher temperature. The thirdfeed water 36 flows into a heater 47, and is heated by a heat recoverywater 40 so as to have a higher temperature. After that, the third feedwater 36 flows into a middle location of the solar heat heater 22 andmerges with the second feed water 35, which has been heated at aposition in the solar heat hater 22 that is upstream of a merging point34.

It is preferable that the merging point 34 is located such that thetemperature of the second feed water 35 and the temperature of the thirdfeed water 36 are substantially equal to each other, but it is not amust. Both of a heat quantity of a solar heat and a heat quantity of anindustrial exhaust heat may considerably vary, but a property of thesteam 2 flowing into the steam turbine 1 should not considerably vary.In a general steam turbine plant, a temperature and a pressure of thesteam 2 are measured, and the temperature and the pressure should notconsiderably vary. In a general steam turbine plant, a flow rate of thesteam is obtained by measuring a flow rate of the water 42, for example,and the flow rate of the steam 2 should not considerably vary.

For this reason, it is preferable that flow rates of the heating mediumare increased or decreased by adjusting outputs of heating medium pumps26 and 27, that an output of the feed pump 6 is adjusted so as to adjusta flow rate and a pressure of the feed water 42, that a flow rate ratiobetween the second feed water 35 and the third feed water 36 is adjustedby adjusting opening degrees of valves 37 and 38, and that, depending oncases, a flow rate of the heat recovery water 40 is increased ordecreased by adjusting an output of a recovery water pump 41, in orderthat the temperature, the pressure and the flow rate of the steam 2 donot considerably vary. At this time, although not shown, a flow-rateadjusting valve may be installed on a downstream of the feed pump 6, soas to adjust the flow rate and the pressure of the feed water 42 byadjusting an opening degree of the flow-rate adjusting valve. The mergedwater is heated by the solar heat heater 22 at a position downstream ofthe merging point 34 so as to change to a steam 2. Then, the steam 2flows into a steam turbine 1. When the third feed water 36 is notcirculated through a heater 47 for some reason or other, the valves 37and 38 are totally closed. Since a flow rate of the third feed water 36is sufficiently smaller than a flow rate of the second feed water 35,even if the flow rate of the steam 2 somewhat lowers, the steam turbine1 can be operated. During a nighttime when a solar heat is not obtainedat all or is obtained insufficiently, an operation similar to theseventeenth technique is carried out.

As the Rankine cycle, a received heat quantity is increased by a heatreceived from the heat recovery water 40, so that a flow rate of thesteam 2 is increased to increase an output, while a steam turbine inlettemperature is unchanged. An efficiency of the Rankine cycle isdetermined only by the area ratio in the TS line diagram, regardless ofa flow rate. Since all the steam constitutes the Rankine cycle of a hightemperature and a high pressure, an efficiency according to the thisembodiment is equal to the technique shown in FIG. 17.

According to this embodiment, a power generation can be carried out,without lowering an efficiency from the technique shown in FIG. 17, byusing the industrial exhaust heat which is discharged without beingefficiently used.

In FIG. 12, although an extracted steam 9 from the steam turbine 1 and afeed water heater 8 do not exist, they may exist. In addition, a heatstorage tank 25 may be omitted. However, in this case, the steam turbineplant can be operated only when it can receive a solar heatsufficiently.

The aforementioned above embodiments are taken by way of examples, andthe scope of the invention is not limited thereto.

-   1 Steam turbine-   2 Steam-   3 Turbine exhaust air-   4 Condenser-   5 Condensation-   6 Feed pump-   7 Coal fired boiler-   8 Extracted steam-   9 Feed water heater-   10 Drainage water-   11 Waste-   12 Combustion air-   13 Exhaust combustion gas-   14 Gas turbine exhaust air-   15 Exhaust heat boiler-   18 Waste boiler-   19 Geothermal steam-   20 Hot water-   21 Ground-   22 Solar heat heater-   23 Solar heat collector-   24 Heating medium-   25 Heat storage tank-   26 Heating medium pump-   27 Heating medium pump-   28 Valve-   29 Valve-   30 Valve-   31 Valve-   32 Saturated water line-   33 Saturated steam line-   34 Merging point-   35 Second feed water-   36 Third feed water-   37 Valve-   38 Valve-   39 Exhaust heat source-   40 Heat recovery water-   41 Heat recovery water pump-   42 Feed water-   43 Coal-   44 Waste exhaust combustion gas-   46 Fuel battery or internal combustion engine-   47 Heater

1. A steam turbine plant comprising: a steam turbine; and a heating unitconfigured to heat a working fluid to be supplied to the steam turbine;wherein: the heating unit is configured to heat the working fluid by afirst heat source using a fossil fuel or a second heat source using anextracted steam from the steam turbine; and the heating unit isconfigured to further heat the working fluid in a low temperature zoneby a third heat source other than a solar heat, the third heat sourcenot using a fossil fuel.
 2. The steam turbine plant according to claim1, wherein the third heat source includes an exhaust combustion gas of awaste combustion furnace.
 3. The steam turbine plant according to claim1, wherein the third heat source includes a steam or a hot water takenout from a ground.
 4. The steam turbine plant according to claim 1,wherein the third heat source includes an industrial exhaust heat. 5.The steam turbine plant according to claim 1, wherein the third heatsource includes an exhaust heat of a fuel battery or an internalcombustion engine.
 6. The steam turbine plant according to claim 1,wherein the first heat source includes an exhaust gas of a gas turbinedriven by burning a fossil fuel.
 7. The steam turbine plant according toclaim 1, wherein the first heat source includes an exhaust combustiongas in a coal fired boiler.
 8. A steam turbine plant comprising: a steamturbine; and a heating unit configured to heat a working fluid to besupplied to the steam turbine; wherein: the heating unit is configuredto heat the working fluid by a fourth heat source using a solar heat ora second heat source using an extracted steam from the steam turbine;the heating unit is configured to further heat the working fluid in alow temperature zone by a fifth heat source other than a solar heat; andthe fifth heat source includes an industrial exhaust heat.
 9. A steamturbine plant comprising: a steam turbine; and a heating unit configuredto heat a working fluid to be supplied to the steam turbine; wherein:the heating unit is configured to heat the working fluid by a fourthheat source using a solar heat or a second heat source using anextracted steam from the steam turbine; the heating unit is configuredto further heat the working fluid in a low temperature zone by a fifthheat source other than a solar heat; and the fifth heat source includesan exhaust heat of a fuel battery or an internal combustion engine. 10.The steam turbine plant according to claim 8, wherein the fourth heatsource uses a heat source storing a solar heat.
 11. The steam turbineplant according to claim 1, wherein: the heating unit includes a firstheater using the first heat source and a third heater using the thirdheat source; and all or a part of the first heater and the third heaterare arranged in parallel with respect to the working fluid.
 12. Thesteam turbine plant according to claim 1, wherein: the heating unitincludes a second heater using the second heat source and a third heaterusing the third heat source; and all or a part of the second heater andthe third heater are arranged in parallel with respect to the workingfluid.
 13. The steam turbine plant according to claim 1, wherein: theheating unit includes a first heater using the first heat source and athird heater using the third heat source; and all or a part of the firstheater and the third heater are arranged in series with respect to theworking fluid.
 14. The steam turbine plant according to claim 13,wherein the third heater is arranged on an upstream side of the firstheater.
 15. The steam turbine plant according to claim 1, wherein: theheating unit includes a second heater using the second heat source and athird heater using the third heat source; and all or a part of thesecond heater and the third heater are arranged in series with respectto the working fluid.
 16. The steam turbine plant according to claim 15,wherein the third heater is arranged on an upstream side of the secondheater.
 17. The steam turbine plant according to claim 8, wherein: theheating unit includes a fourth heater using the fourth heat source and afifth heater using the fifth heat source; and all or a part of thefourth heater and the fifth heater are arranged in parallel with respectto the working fluid.
 18. The steam turbine plant according to claim 8,wherein: the heating unit includes a second heater using the second heatsource and a fifth heater using the fifth heat source; and all or a partof the second heater and the fifth heater are arranged in parallel withrespect to the working fluid.
 19. The steam turbine plant according toclaim 8, wherein: the heating unit includes a fourth heater using thefourth heat source and a fifth heater using the fifth heat source; andall or a part of the fourth heater and the fifth heater are arranged inseries with respect to the working fluid.
 20. The steam turbine plantaccording to claim 19, wherein the fifth heater is arranged on anupstream side of the fourth heater.
 21. The steam turbine plantaccording to claim 8, wherein the heating unit includes a second heaterusing the second heat source and a fifth heater using the fifth heatsource; and all or a part of the second heater and the fifth heater arearranged in series with respect to the working fluid.
 22. The steamturbine according to claim 21, wherein the fifth heater is arranged onan upstream side of the second heater.
 23. The steam turbine plantaccording to claim 17, wherein a property of the working fluid flowinginto the steam turbine is restrained from varying, by adjusting at leastone or more of a flow rate of the working fluid, a received heatquantity from the third heat source or from the fifth heat source, and arate between flowrates of the working fluid to parallel flow paths. 24.The steam turbine plant according to claim 19, wherein a property of theworking fluid flowing into the steam turbine is restrained from varying,by adjusting at least one or more of a flow rate of the working fluid,and a received heat quantity from the third heat source or from thefifth heat source.
 25. The steam turbine plant according to claim 9,wherein the fourth heat source uses a heat source storing a solar heat.26. The steam turbine plant according to claim 9, wherein: the heatingunit includes a fourth heater using the fourth heat source and a fifthheater using the fifth heat source; and all or a part of the fourthheater and the fifth heater are arranged in parallel with respect to theworking fluid.
 27. The steam turbine plant according to claim 9,wherein: the heating unit includes a second heater using the second heatsource and a fifth heater using the fifth heat source; and all or a partof the second heater and the fifth heater are arranged in parallel withrespect to the working fluid.
 28. The steam turbine plant according toclaim 9, wherein: the heating unit includes a fourth heater using thefourth heat source and a fifth heater using the fifth heat source; andall or a part of the fourth heater and the fifth heater are arranged inseries with respect to the working fluid.
 29. The steam turbine plantaccording to claim 28, wherein the fifth heater is arranged on anupstream side of the fourth heater.
 30. The steam turbine plantaccording to claim 9, wherein the heating unit includes a second heaterusing the second heat source and a fifth heater using the fifth heatsource; and all or a part of the second heater and the fifth heater arearranged in series with respect to the working fluid.
 31. The steamturbine according to claim 30, wherein the fifth heater is arranged onan upstream side of the second heater.
 32. The steam turbine plantaccording to claim 18, wherein a property of the working fluid flowinginto the steam turbine is restrained from varying, by adjusting at leastone or more of a flow rate of the working fluid, a received heatquantity from the third heat source or from the fifth heat source, and arate between flowrates of the working fluid to parallel flow paths. 33.The steam turbine plant according to claim 26, wherein a property of theworking fluid flowing into the steam turbine is restrained from varying,by adjusting at least one or more of a flow rate of the working fluid, areceived heat quantity from the third heat source or from the fifth heatsource, and a rate between flowrates of the working fluid to parallelflow paths.
 34. The steam turbine plant according to claim 17, wherein aproperty of the working fluid flowing into the steam turbine isrestrained from varying, by adjusting at least one or more of a flowrate of the working fluid, a received heat quantity from the third heatsource or from the fifth heat source, and a rate between flowrates ofthe working fluid to parallel flow paths.
 35. The steam turbine plantaccording claim 21, wherein a property of the working fluid flowing intothe steam turbine is restrained from varying, by adjusting at least oneor more of a flow rate of the working fluid, and a received heatquantity from the third heat source or from the fifth heat source. 36.The steam turbine plant according claim 28, wherein a property of theworking fluid flowing into the steam turbine is restrained from varying,by adjusting at least one or more of a flow rate of the working fluid,and a received heat quantity from the third heat source or from thefifth heat source.
 37. The steam turbine plant according claim 30,wherein a property of the working fluid flowing into the steam turbineis restrained from varying, by adjusting at least one or more of a flowrate of the working fluid, and a received heat quantity from the thirdheat source or from the fifth heat source.